a. Field of the Invention
The present invention relates generally to apparatus for preventing marine fuel spills, and, more particularly, to an apparatus for preventing the spilling of fuel from a vent line when filling the fuel tank of a boat or other marine craft.
b. Related Art
Fuel systems for boats and other marine craft must be provided with a vent, both to allow the fuel tank to be filled and to permit fuel to flow from the tank to the engine during operation. During refueling, the vent allows air to escape from the tank as it is displaced by the fuel (i.e., gasoline or diesel) entering through the main filler tube. As the tank reaches its capacity, the fuel tends to rush up the vent line and “spit” out the vent opening at the exterior of the hull, which is in fact commonly relied on as an indication that the tank is full.
Unfortunately, any fuel ejected from the vent opening will be discharged into the water, in violation of various governmental regulations. Boat owners have therefore resorted to a variety of stratagems for capturing the fuel ejected from the vent opening, none being entirely satisfactory. For example, many fueling docks provide their customers with a small paper cup in which to catch the gasoline or diesel as it spits from the vent opening; not only is the cup cumbersome and annoying to use, but the imperfect nature of this technique almost invariably results in some of the fuel being spilled into the water.
A number of attempts have been made at providing an installed system for preventing fuel from being discharged from the vent opening, several of which having employed an overflow or collection tank that is mounted in the vent line. This approach has the potential for obviating the difficulties of trying to catch the fuel as it is discharged from the vent opening, but again none have been entirely successful.
For example, U.S. Pat. No. 6,929,039 shows a simple overflow tank that is mounted in parallel with the vent line to capture excess fuel, with restrictive orifices that control the rate at which fuel is able to enter the tank. However, there is still the risk that fuel will be discharged from the vent opening, if the overflow tank becomes full or the rate of flow is excessive so that it bypasses the tank.
U.S. Pat. No. 4,854,469 shows a collection tank that utilizes an arrangement of openings and baffles to prevent the fuel from flowing directly to the vent opening, but that otherwise exhibits the same problems as the device described in the preceding paragraph. The tank shown in U.S. Pat. No. 4,854,469 has the advantage of a window that enables the operator to see the level of fuel that has been collected and therefore stop filling before fuel overflows through the vent opening; however, mounting the collection tank so it can be seen from the exterior of the boat when refueling (for example, by cutting a hole in the deck or cockpit wall), is simply impractical for most craft.
U.S. Pat. No. 5,229,766 shows a more sophisticated device, that uses a two-stage, tapered guide tube for the fuel, a sliding float within the tube, reed switches that are actuated by a bar magnet mounted on top of the float, a switch circuit that activates an audible alarm in response to actuation of the reed switches, a plunger-operated reset mechanism, and so on. Although the use of an audible alarm avoids the problem of having to view the tank directly, the complexity of this device and its use of numerous dedicated components render it uneconomical to produce, particularly in the marine products market where high retail markups are the norm.
Accordingly, there exists a need for an apparatus for preventing the discharge of gasoline, diesel, or other liquid fuel from the vent opening of a boat or other marine craft while filling the main tank thereof. Furthermore, there exists a need for such an apparatus that is effective when the main tank is being filled at fast rates as well as slow rates. Still further, there exists a need for such an apparatus that provides the operator with an effective warning before the capture tank is filled. Still further, there exists a need for such an apparatus that can be conveniently mounted on boats and other marine craft having conventional construction. Still further, there exists a need for such an apparatus that is durable and reliable in operation. Still further, there exists a need for such an apparatus that is economical to produce and that can be competitively priced in the marine products market.